The present invention relates to an air cleaner for an internal combustion engine.
An air cleaner for filtering intake air is provided in the intake passage of an internal combustion engine (for example, Japanese Laid-Open Patent Publication No. 2007-32409). The air cleaner disclosed in the publication includes a first housing, which has an opening and an inlet port, and a second housing, which has an opening facing the opening of the first housing and an outlet port. Also, a filter element is provided between the opening of the first housing and the opening of the second housing.
The air cleaner of the publication includes an adsorption member for adsorbing fuel vapor of the internal combustion engine on the inner surface of the second housing. A gap exists between the inner surface and the adsorbing member. Specifically, the adsorption member has an adsorption sheet containing activated carbon or the like for adsorbing fuel vapor and a frame provided at the periphery of the adsorption sheet. The adsorption member is attached to the second housing by fixing the frame to fixing pins protruding from the inner surface of the second housing.
With the air cleaner of the publication, fuel vapor flowing backward through the intake passage away from the combustion chamber is adsorbed by the adsorption member while the engine is in a stopped state. Further, during operation of the engine, the fuel component adsorbed by the adsorption member passes through the gap together with the intake air and is carried away toward the combustion chamber. This purges the adsorption member, so that the adsorption performance is restored.
Further, with the above-described air cleaner, since the adsorption member is provided along the inner surface of the second housing, the flow of intake air is less likely to be disturbed and the flow resistance is less likely to be increased than in the configuration in which an adsorption member is provided along the cross section of the flow path of the intake air.
In the case of the air cleaner described in Japanese Laid-Open Patent Publication No. 2007-32409, although the adsorption member is provided along the inner surface of the second housing, it is necessary to provide a gap between the adsorption member and the inner surface of the second housing so that the fuel component adsorbed by the adsorption member is carried away by the intake air. That is, the adsorption member must be arranged to be separated from the inner surface of the second housing. Thus, the adsorption member disturbs the flow of intake air, and it is difficult to suppress the increase in the flow resistance.